JB4 N55 Overboosting?

[Rub10s]

Only mods I have are JB4 (non iso) + burger intake. Live in Las Vegas, so we get crappy 91 octane.

Recently in map 1 I've noticed my boost spiking more than normal. At partial throttle in 3rd I've seen the boost shoot up to 17ish (as judged by the fuel gauge). At WOT it will settle around 15psi, but shouldn't it be limited to 12 or 13?

I tried map 4 today, and in 2nd at WOT was around 12psi, but I was under the impression the boost shouldn't go above 8 on the stock map?

It's about 75 degrees here in Vegas, so not cool enough that it should be increased so much.

I'll try and do some logs tonight, but has anyone seen anything like this? Connections all seem fine from what I can eyeball.

3rd gear pull in map 1 log

[135Pats]

We need logs. Partial throttle behavior will be tough to glean much from. When it’s hotter out, your turbos will have to work harder to move equivalent air mass. And the fuel gauge is a gimmick, it’s cool but not useful for seriously measuring an overboost situation.

[Rub10s]

Originally Posted by 135Pats

We need logs. Partial throttle behavior will be tough to glean much from. When it’s hotter out, your turbos will have to work harder to move equivalent air mass. And the fuel gauge is a gimmick, it’s cool but not useful for seriously measuring an overboost situation.

Here is a quick 2nd gear run in map 1. I'll try later to get some different logs in different maps.

Did a partial throttle acceleration where you can see the boost went to about 16. Not crazy, but I'm just surprised it's doing this.

At WOT it seems to nail 12-13.

LOG

[135Pats]

Originally Posted by Sheldon

Here is a quick 2nd gear run in map 1. I'll try later to get some different logs in different maps.

Did a partial throttle acceleration where you can see the boost went to about 16. Not crazy, but I'm just surprised it's doing this.

At WOT it seems to nail 12-13.

LOG

Boost is measured in the manifold, so if you suddenly let off the throttle, it could read something ridiculous like 25 pounds when in fact it’s not actually pushing any boost. I would not worry about boost control under partial throttle unless something is just wayyyy off.

Post up a 3rd gear log when you can. 2nd gear doesn’t load the motor enough, so it’s not going to show us much.

[edisapimp]

When I lived there, every 76 gas station had 100 octane at the pump. Is that still the case?

[Rub10s]

Originally Posted by edisapimp

When I lived there, every 76 gas station had 100 octane at the pump. Is that still the case?

Yeah the "rebel" stations have 100 octane. I ran it through the colder months to play with higher boost in map 5/7

[zzimbile]

Nice to see a fellow e88-er in vegas

[edisapimp]

Put 100 octane then, foo!!!

[zzimbile]

I havent seen 100 octane, but then again i havent looked very hard. Going to check it out today

[Rub10s]

Originally Posted by zzimbile

I havent seen 100 octane, but then again i havent looked very hard. Going to check it out today

Almost every rebel station has it on the same pump set that they have Diesel. I know for sure the Rebel on Sunset and Pecos has it, that's where I get it.

[edisapimp]

I used to love that shit man! Before test n tune nights at LVMS I would run my nissan down to empty then go pay $3.95/gallon for the 100octane from the 76 at Trop and Arville, turn up the boost and love life.

Interestingly, I just paid $4.35/gal for 93 Shell V-Power this morning. What a difference 10 years makes.

[zzimbile]

Originally Posted by Sheldon

Almost every rebel station has it on the same pump set that they have Diesel. I know for sure the Rebel on Sunset and Pecos has it, that's where I get it.

Thats good to know, thanks. I knew they had e85 but never thought to look for 100

[Rub10s]

Originally Posted by edisapimp

I used to love that shit man! Before test n tune nights at LVMS I would run my nissan down to empty then go pay $3.95/gallon for the 100octane from the 76 at Trop and Arville, turn up the boost and love life.

Interestingly, I just paid $4.35/gal for 93 Shell V-Power this morning. What a difference 10 years makes.

WOW! Last time I bought 100 oct it was $8/gallon

[Rub10s]

OK here is a log that has a strong 3rd gear pull. Boost starts at 15 then tapers down to 12. This was in map 1...

LOG

[Rub10s]

Sent the log to Terry and it looks like the JB4 is doing it's job of hitting the targeted boost, but the target it higher than it should be. Terry thinks my car might have a flash tune before I got it, I guess I'll just use map 4 unless I'm running higher octane.